Polycarbonate has found many uses as a class of materials because it combines, in general, a high level of heat and impact resistance, good dimensional stability, and good insulating and non-corrosive properties. The components typically used in the preparation of polycarbonate are a dihydric phenol and a carbonate precursor. Polycarbonate prepared, for example, from an ortho-substituted dihydric phenol frequently exhibits desirable properties such as a high level of hydrolytic stability and resistance to thermal deformation. When different kinds of dihydric phenols are used to prepare a polycarbonate, such as an ortho-substituted dihydric phenol and a non-ortho-substituted dihydric phenol, a carbonate copolymer, or copolycarbonate, results. However, the properties of a copolycarbonate may differ from those of homopolycarbonates formed from the respective monomers.
Depending on the distribution along the polymer chain of the respective residues of different kinds of dihydric phenols used in forming a copolycarbonate, two of the sequence classifications into which a linear copolycarbonate commonly falls are that of a random or a block copolycarbonate. It is usually found that a random copolymer has physical and chemical properties which are about the weighted average of those of homopolymers prepared from the separate comonomers. Block copolymers, on the other hand, generally display properties which represent both an average of the individual homopolymer properties as well as properties derived from the individual homopolymers themselves.
Often, the fact that a random copolymer is characterized (with insignificant exceptions) by such an average of properties makes it a preferred choice of material compared to a block copolymer because some of the behavior of a block copolymer will always be derived from the properties of homopolymeric segments formed from the separate comonomers. Consequently, it would be advantageous to have a process for the preparation of random copolycarbonate, particularly a random copolycarbonate made from ortho-substituted dihydric phenols and non-ortho-substituted dihydric phenols.